Context Matters in Semantically Controlled Language Generation for Task-oriented Dialogue Systems

Ye Liu, Wolfgang Maier, Wolfgang Minker, Stefan Ultes


Abstract
This work combines information about the dialogue history encoded by pre-trained model with a meaning representation of the current system utterance to realise contextual language generation in task-oriented dialogues. We utilise the pre-trained multi-context ConveRT model for context representation in a model trained from scratch; and leverage the immediate preceding user utterance for context generation in a model adapted from the pre-trained GPT-2. Both experiments with the MultiWOZ dataset show that contextual information encoded by pre-trained model improves the performance of response generation both in automatic metrics and human evaluation. Our presented contextual generator enables higher variety of generated responses that fit better to the ongoing dialogue. Analysing the context size shows that longer context does not automatically lead to better performance, but the immediate preceding user utterance plays an essential role for contextual generation. In addition, we also propose a re-ranker for the GPT-based generation model. The experiments show that the response selected by the re-ranker has a significant improvement on automatic metrics.
Anthology ID:
2021.icon-main.18
Volume:
Proceedings of the 18th International Conference on Natural Language Processing (ICON)
Month:
December
Year:
2021
Address:
National Institute of Technology Silchar, Silchar, India
Venue:
ICON
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Publisher:
NLP Association of India (NLPAI)
Note:
Pages:
139–151
Language:
URL:
https://aclanthology.org/2021.icon-main.18
DOI:
Bibkey:
Cite (ACL):
Ye Liu, Wolfgang Maier, Wolfgang Minker, and Stefan Ultes. 2021. Context Matters in Semantically Controlled Language Generation for Task-oriented Dialogue Systems. In Proceedings of the 18th International Conference on Natural Language Processing (ICON), pages 139–151, National Institute of Technology Silchar, Silchar, India. NLP Association of India (NLPAI).
Cite (Informal):
Context Matters in Semantically Controlled Language Generation for Task-oriented Dialogue Systems (Liu et al., ICON 2021)
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PDF:
https://aclanthology.org/2021.icon-main.18.pdf